ikev2: fix coverity warning
ikev2: fix coverity warning

Type: fix

Change-Id: Iee96b3ea3e71ec248c3c3c98d153a08372b5faf0
Signed-off-by: Filip Tehlar <9891019d6f5d48a43af8fb71dfec78974db6001d@cisco.com>

chrisy/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,FDio/vpp